Step 1: Estimate the Solution
The equation given is
\[ \frac{b}{7.8} = -2.15 \]
To estimate the value of \(b\), we can multiply both sides by 8 (a close estimation of 7.8) to simplify our calculations. Thus, we have:
\[ b \approx -2.15 \times 8 \]
Calculating this gives:
\[ -2.15 \times 8 = -17.2 \]
So, our estimate for \(b\) is approximately \(-17.2\).
Step 2: Solve the Equation
Now, let’s solve the equation exactly. We start from the original equation:
\[ \frac{b}{7.8} = -2.15 \]
To isolate \(b\), we can multiply both sides by 7.8:
\[ b = -2.15 \times 7.8 \]
Now let’s perform the multiplication:
\[ b = -16.83 \]
Step 3: Comparison of Estimate and Actual Answer
Our estimate for \(b\) was \(-17.2\) and we found the exact solution to be \(-16.83\).
Comparing the two:
- Estimate: \(-17.2\)
- Exact Solution: \(-16.83\)
The exact solution of \(-16.83\) is quite close to the estimate of \(-17.2\), indicating that our estimation method was effective.
Conclusion
In conclusion, my estimation was reasonably close to the actual solution of the equation. The estimate of \(-17.2\) gave a good approximation, as \(-16.83\) is only slightly higher than \(-17.2\). This demonstrates that using a rounded number for calculations can provide a useful initial insight into the solution.